Device for producing electric flashlight



z Iv Nov. 22, v1955 J. NESSEL DEVICE FOR PRODUCING ELECTRIC FLASHLIGHTFiled Nov. 8, 1952 Fig.7

United States PatentO DEVICE FOR PRODUCING ELECTRIC FLASHLIGHT JiriNessel, Munich, Germany Application November 8, 1952, Serial No. 319,498

7 Claims. (Cl. 315-234) The present invention relates to a device forproducing electric flashlight, especially for photographic purposes,which, between the electrodes of a gas-filled discharge tube, produces adischarge of a high luminous intensity by means of the electrical energyput into one or more condensers.

Some types of such devices have already been known, which produce theelectrical energy for the discharge tube by means of several condensersconnected in series, the voltage of which is lower than that of thedischarge tube.

This involves the advantage of allowing to use low voltage condensers,which, since such devices use electrolytic condensers, are morereliable, easier to manufacture, and, thereby, cheaper.

On the other hand, there is the inconvenience of the high manufacturingtolerances inevitable with electrolytic condensers, which manifestthemselves in the fact that, with condensers of the same rated capacitythe effective capacity and the internal resistances diifer considerably.These tolerances still more increase after a lengthened use. Thus, withsuch condensers connected in series, considerable differences of voltageand energy can appear, so that under certain circumstances the workingvoltage of a condenser or several condensers will be exceeded, which,already after a short service period, can lead to the destruction of theoverloaded condenser or condensers.

The present invention remedies all these inconveniences by creating adevice which effects the connection in series of condensers connected inparallel simultaneously with actuating the ignition.

In order to obtain the high voltage required for the tube, suchcondensers are charged while connected in parallel, after which thecondensers charged are connected in series and then discharged in theusual way over the electrodes of the ignited tube.

According to the embodiment hereinafter described, this can be realizedby closing, at the moment of igniting, one or more open bridging leadsbetween the intermediate leads which connect the like poles of thecondensers with each other, the said intermediate leads comprisingresistances which, at the moment of the discharge of the condensers,temporarily act as automatic disconnecting switches.

For that purpose a current producer of an accordingly low voltage willdo, which is considerably cheaper and which means considerable savingsof weight, a feature of outstanding importance with portable devices.

Some further features and advantages of the invention will beillustrated in the following description of the drawings representingthe switch diagrams of two preferably chosen embodiments of the same.

Fig. l is a switch diagram of a device according to the inventionequipped with a discharge tube of the usual type comprising two mainelectrodes.

Fig. 2 shows another embodiment of the invention, with which a dischargetube comprising three electrodes is used.

Fig. 1 represents a device for producing electric flashlight with ausual gas discharge tube 1, comprising an 2,724,792 Patented Nov. 22,1955 anode 2, a cathode 3, and an ignition electrode 4. The dischargecircuit lying close to the two electrodes 2 and 3 of the tube 1 containstwo condensers 5 and 6 as well as the ignition system consisting of theignition coil with the primary winding 10, the secondary winding 11, theignition condenser 13, the resistance 12, and the ignition contact orswitch 14. The condenser 6 is connected to the current-producing circuitconsisting of the battery 7, the protective resistance 8, and thecharging switch 9.

The two condensers 5 and 6 are connected in parallel, i. e. theirhomopolar coatings are interconnected. A lead 17 connects the positivecoatings to each other and to the anode 2, another lead connects thenegative coatings with each other, over the resistance 12 of theignition system operated in the usual way, to the cathode 3. Accordingto the invention, between the two intermediate leads 17 and 18, abridging lead 19 is provided, which is interrupted by the ignitionswitch 14. Besides, a resistance is arranged in the lead 17.

As soon as, after charging the condensers 5 and 6, the open bridginglead 14 is closed, which can be done either by operating the ignitionswitch 14 by hand, or by means of a contact synchronously operated fromthe shutter of the camera, the tube 1 will not only receive an ignitionimpulse at the ignition electrode 4, but, at the same time, also theconnection in parallel of the condensers 5 and 6 will be transformedinto a connection in series, so that the voltages of the condenserssummed up will yield the voltage required for the tube. Then thedischarge can take place. As the resistance offered by the gasdischarging tube, at the moment of the discharge, is but a fraction ofthe resistances 16 and 12, the electrical energy resulting from the twocondensers will discharge over the tube 1. Thus, the resistances 16 and12 will transitorily act as automatic disconnecting switchesinterrupting the intermediate leads 17 and 18 at the moment of thedischarge of the ignition tube 1, so that the bridging lead 19 closedwill establish at that very moment the connection in series of thecondensers.

In order to remedy the inconveniences which, as hereinbefore mentioned,might result from the fact that the condensers 5 and 6, despite the samerated capacity values, difier considerably in their effective capacityand their internal resistances, the bridging lead 19, as shown in Fig.2, may be connected to a third electrode 15 provided in the tube 1.Then, with the tube ignited, the condenser 5 alone can discharge overthe electrodes 2 and 15, and the condenser 6 alone can discharge overthe electrodes 2 and 3, so that any existing difference of voltage,capacity, and, accordingly, energy will not act in a sense that thecondenser possessing the higher electrical energy might load the othercondenser, in the final phase of the discharge, by its dischargingcurrent with an opposite polarity tending to form it in an oppositesense. The use of a third electrode 15 presents the advantage that thevalues of the condensers can vary without any prejudice, not only withinthe usual tolerances, but that it also allows different values to bechosen on purpose. Thus, if the condenser 5 is small, the currentflowing over the contact 14 will also grow small, so that theflash-releasing contact can be used direct on the camera itself as anignition contact. The selection of different capacity values for thecondensers 5 and 6 will also result in differences of the outsidedimensions, which can be taken advantage of for their spatialdisposition. Thus, for instance, it will be possible to lodge thesmaller condenser 5 in the flashlight system consisting of the reflectorand tube.

The present invention, when combining the ignition contact 14 with thecharging switch 9 into a two-pole change-over switch, also presents theadvantage of easier handling and attendance.

I claim:

1. Apparatus for producing a high intensity flash of light forphotographic purposes in synchronism with the opening of the shutter ofa camera, which comprises, a gas-filled discharge tube having twoelectrodes between which the principal discharge occurs, a triggeringelectrode, a triggering circuit including a control capacitor having ashunting resistor and having one pole connected to a pulsingauto-transformer having primary and secondary windings connectedrespectively to one of said two electrodes and the triggering electrode,a D. C. source, a power capacitor connected across the source and alsoacross said two electrodes but with a current blocking resistor betweenone pole and an electrode, a second power capacitor also connectedacross the source and across the two electrodes, but with one polethereof connected in series with the triggering circuit whereby theshunting resistor and primary winding are interposed between said onepole and said one electrode, and a switch connected between oppositepoles of the respective power capacitors.

2. Apparatus for producing a high intensity flash of light forphotographic purposes in synchronism with the opening of the shutter ofa camera, which comprises a gas-filled discharge tube having twoelectrodes between which the principal discharge occurs, a triggeringelectrode and a triggering circuit between said triggering electrode andone of said two electrodes, a source of D. C. power of relatively lowvoltage, two power capacitors each connected across the source andacross the two electrodes, but each having a direct current impedance inthe loop defined by itself and the two electrodes to the exclusion ofthe loop formed by the other capacitor with the electrodes, and a switchbetween opposite poles of the power capacitors adapted to be closed todischarge the power capacitors in series through the gaseous dischargedevice, the triggering circuit connected with one of said opposite polesfor acquiring activation also through the closing of said switch.

3. Apparatus as described in claim 2 in which the triggering circuitincludes a condenser and shunt resistor for leaking the charge oif thecondenser, and the said shunt resistor serves as the direct currentimpedance in one of said above defined loops, at part of the triggeringcircuit being included in series in said last mentioned loop.

4. Apparatus as described in claim 2 in which the triggering circuitincludes a condenser and shunt resistor for leaking the charge oif thecondenser, and the said shunt resistor serves as the direct currentimpedance in one of the said defined loops, a part of the triggeringcircuit being included in series in said last mentioned loop, saidtriggering circuit including a pulse transformer having primary andsecondary windings, said part being the primary winding.

5. Apparatus as described in claim 2 in which the gaseous dischargedevice has a third electrode connected to one side of said switch suchas to provide an intermediate condenser discharge path through saidtube.

6. Apparatus as described in claim 2 in which the gaseous dischargedevice has a third electrode connected to one side of said switch suchas to provide an intermediate condenser discharge path through said tubeand in which one of said power condensers only is in series with saidswitch during discharge, so that the current flow through said switch islow.

7. A device as described in claim 6 in which said one power condenser isof smaller capacity than the other, and is arranged to dischargeinitially.

References Cited in the file of this patent UNITED STATES PATENTS2,447,832 Abend et a1 Aug. 24, 1948 2,485,037 Clark Oct. 18, 19492,493,137 Hansen Jan. 3, 1950 2,628,331 Rockafellow Feb. 10, 1953

